[FFmpeg-devel] [PATCH] (for discussion): nvenc: fix wrong aspect ratio for 720x576 and 720x480 resolution

[Philip Langdale]

On Mon, 13 Feb 2017 08:52:34 +0100
Miroslav Slugeň <thunder.m at email.cz> wrote:

> Dne 12.2.2017 v 23:20 Philip Langdale napsal(a):
> > On Sun, 12 Feb 2017 22:43:41 +0100
> > Miroslav Slugeň <thunder.m at email.cz> wrote:
> >  
> >> Dne 12.2.2017 v 22:31 Timo Rothenpieler napsal(a):  
> >>> On 2/12/2017 10:25 PM, Miroslav Slugeň wrote:  
> >>>> This patch is for discussion only, not ready to commit yet and
> >>>> maybe newer will be.
> >>>>
> >>>> NVENC in current CUDA 8 SDK is setting wrong aspect ratio when
> >>>> encoding resolution 720x576 and 720x480 and using AR 4:3 or 16:9
> >>>> it will encode to h264 header that 15:11 and 20:11 is used. This
> >>>> is very very very ugly way how to fix it. I hope someone in
> >>>> NVIDIA will fix this soon, because all encoded streams are not
> >>>> displayed correctly for example in videojs player.  
> >>> nvenc.c had some compensation for this, which was somewhat
> >>> recently removed, because nvidia fixed something regarding it:
> >>>
> >>> http://git.videolan.org/?p=ffmpeg.git;a=commit;h=829db8effd76b579ae9aca5ee8f85d3ade6af253
> >>> _______________________________________________
> >>> ffmpeg-devel mailing list
> >>> ffmpeg-devel at ffmpeg.org
> >>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel  
> >> I know that, i am monitoring all nvenc and cuvid changes in ffmpeg.
> >>
> >> Fix is not working anymore in current drivers. What is working is
> >> if you set aspect ratio 16000x9001 it will give you almost correct
> >> output, but fixing this in h264 SPP is better solution.
> >>
> >> M.
> >> _______________________________________________
> >> ffmpeg-devel mailing list
> >> ffmpeg-devel at ffmpeg.org
> >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel  
> > If it's still happening, let's just restore the original workaround.
> > But I stopped being able to reproduce the problem locally, and I
> > can't reproduce it right now with a 720x576 sample.
> >
> > Note that the SDK is completely irrelevant to playback behaviour.
> > The CUDA SDK doesn't include current cuvid/nvenc headers and the
> > Video SDK isn't required because we bundle/reimplement headers with
> > ffmpeg.
> >
> > You are likely not using a new enough driver release to have the
> > fix in it. I'm using 378.09 here.
> >
> > --phil
> >  
> I am using current STABLE drivers 375.26, because BETA drivers 378.09 
> caused some crashes while encoding on NVENC.
> 
> I tested this on BETA drivers too and it is still same.
> 
> Original workaround is not working anymore :(
> 
> INPUT: Stream #0:0[0x401]: Video: mpeg2video (Main) ([2][0][0][0] / 
> 0x0002), yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], 25
> fps, 25 tbr, 90k tbn, 50 tbc
> 
> OUTPUT: Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] /
> 0x001B), yuv420p(progressive), 720x576 [SAR 16:11 DAR 20:11], 25 fps,
> 25 tbr, 90k tbn, 50 tbc
> 
> COMMAND: ffmpeg -deint adaptive -hwaccel cuvid -c:v mpeg2_cuvid -i 
> "in.ts" -y -c:v h264_nvenc -c:a copy -b:v 1M -preset hq -f mpegts
> "out.ts"
> 
> Also someone else is complaining about this issue: 
> http://superuser.com/questions/1174097/ffmpegnvenc-encoding-strange-aspect-ratio
> 
> M.
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel

Can you point me to a sample that you see this behaviour with? I cannot
reproduce with DVD sources here, which is where I saw the original
problem.

--phil